Electrical plugs for extension cords, particularly power cords used for appliances and power tools, are often removed from the outlet by pulling on some part of the cord rather than by grasping and pulling on the plug itself. The result is that the wire cord can be pulled away from the plug body, causing the removal force to be exerted on the copper wires or the attachment of the copper wires to the power blades of the plug. This force can damage the wires, the blades or the attachement of the two, and possibly expose live wires and cause an electric shock hazard.
A common way to address the problem of excessive forces being exerted on the copper wires or power blades is to mold a strain relief sleeve into the back end of the plug body, and pass the electric wires through the center of the sleeve. The sleeve increases the area of contact between the electric wire jacket and the molded plug and sleeve. This increase in contact area, in turn, reduces the force exerted on the copper wires themselves as well as on the blade connections. In order to accomplish the necessary degree of strain relief, however, the strain relief sleeve must be sufficiently long to assure an adequate contact area. Such a long strain relief sleeve renders the exit from the plug head relatively inflexible, causing the sleeve and cord to extend significantly out from the wall outlet. Since the center of gravity of the plug assembly is significantly displaced from the wall, a torsional force is created on the plug, causing the power blades to tend to pull out of the outlet slots, disconnecting the appliance or partially exposing the live power blades.